Patent application EP-A-1 074 369 has described a method of manufacturing a composite part of given thickness, of convex shape, comprising reinforcing fibres parallel to at least one preferred direction of reinforcement, the said fibres being embedded in a matrix based on a composition containing a resin that can be cured by ionizing radiation, the method comprising the following steps:                arranging the said reinforcing fibres substantially parallel to a plane and impregnating them with the said composition in the liquid state;        exposing the composition containing the said fibres, in a layer of a thickness less than the said given thickness, to an ionizing radiation in order partially to polymerize the resin and obtain a precomposite in which the said composition is in the solid phase;        taking elementary sections from the solid precomposite thus obtained and applying them to a support, the surface of which is non-planar in shape, by stacking them on one another in a number dictated by the said given thickness, and causing them closely to fit the said shape of the support and thus create a stack of stressed elemental sections;        finally subjecting the stack thus obtained to final moulding, under high pressure and at high temperature, so as to continue the polymerization of the resin and thus secure the various sections of precomposite to one another.        
By virtue of the method described, it is possible to obtain composite items that can be used in particular for the manufacture of non-pneumatic tires for motor vehicles.
However, one disadvantage with that method is that it is necessary, after the resin-based matrix solidifies, first of all to cut the solid precomposite into elementary sections, and then to superpose the stressed elementary sections in the desired final shape, this representing a number of successive handling operations which are detrimental from an industrial standpoint and the antithesis to the search for high manufacturing rates.
Patent application EP-A-1 174 250 for its part has proposed:                degassing the arrangement of fibres before impregnating it;        after vacuum impregnation, passing the liquid impregnate through a sizing die, of predefined cross section and predefined form, in order to impose a predetermined shape on the said impregnate, such as, for example, the shape of a thread of round cross section (see, for example, FIGS. 1 to 3) or, more specifically, the shape of a tape (FIGS. 4 to 7);        then, downstream of the die, stabilizing the said thread or tape by substantial solidification of the resin in chambers known as stabilizing chambers comprising a series of irradiation tubes (referenced, for example, 131 and 231 in FIGS. 1 and 4 respectively), emitting in the UV-visible spectrum;        and finally winding said solid (stabilized) thread or tape onto a large-diameter receiving spool (referenced, for example, 141 in FIG. 1), for intermediate storage.        
Composite items can then be prepared by unwinding then rewinding the said thread or tape in solid layers onto any support of appropriate shape.
However, while the previous disadvantages of cutting and assembling prestressed sections are thus eliminated, the second method like the first demands that the resin solidification (polymerization) operation be performed over a substantial thickness of material so that the product is sufficiently “stabilized”, that is to say can be handled without destroying it, for the subsequent operations of manufacturing the final composite items. This requirement in particular involves the use of stabilizing chambers of substantial length, with several irradiation tubes in series, in order to obtain sufficient treatment intensities, particularly where there is a desire to operate at high throughputs.
In the pursuit of its research, the Applicant Company has found a novel method which makes it possible to prepare a very high quality composite item, in the form of a continuous ring, by quite simply omitting the stabilizing chamber and its series of UV irradiation tubes as described in the above application EPA-1 174 250. This appreciably simplifies the manufacturing method and device, and at the same time appreciably reduces the final industrial cost of the intended composite blocks.